by Kim Painter, Special for USA TODAY

by Kim Painter, Special for USA TODAY

Wedges, mats and bolsters sold as infant "sleep positioners" are dangerous and unnecessary, government safety officials say in a renewed warning.

The Consumer Product Safety Commission received reports of 13 infant suffocation deaths linked to the products from 1997 to 2011, says a report out today detailing the previously reported cases. The babies were 21 days to 4 months old, eight were male and four had been born prematurely, say investigators from the commission, the federal Centers for Disease Control and Prevention and the Food and Drug Administration. The findings are in the CDC's Morbidity and Mortality Weekly Report.

Here's one additional finding the experts are especially keen for parents to note: Most of these babies were found on their stomachs after being put to sleep on their sides â?? something the American Academy of Pediatrics has strongly advised against since 2005, but that some parents still do.

Some parents may use positioners to keep babies on their sides. Or they may believe, wrongly, that the products will help keep babies in the recommended position, on their backs, the report says.

The pediatrics academy and other groups say babies should sleep on their backs in a crib with no pillows, stuffed animals or heavy blankets, to reduce the risk of sudden infant death syndrome. Soft items can end up covering a baby's face and blocking breathing.

The FDA is working with manufacturers, and it "continues to review websites that make illegal medical claims related to infant sleep positioners and takes appropriate actions to stop this practice," FDA public affairs specialist Michelle Bolek said in an e-mail.